Introduction
Collagens are major structural components of the extracellular matrix. Type II collagen, also called cartilage collagen, is the major collagen synthesized by chondrocytes. The same type of collagen occurs in the vitreous. Type II collagen is specific for cartilaginous tissues. It is essential for the normal embryonic development of the skeleton, for linear growth and for the ability of cartilage to resist compressive forces. These are synthesized as larger procollagen chains, which contain N- and C-terminal amino acid sequences called propeptides. After secretion into the extracellular matrix, the propeptides are cleaved, forming the mature type II collagen molecule. In addition, defects in processing chondrocalcin, a calcium binding protein that is the C-propeptide of this collagen molecule, are also associated with chondrodysplasia. There are two transcripts identified for this gene.
Alternative Names
Collagen Type II Alpha 1 Chain; Arthroophthalmopathy, Progressive (Stickler Syndrome); Collagen, Type II, Alpha 1; Alpha-1 Type II Collagen; Collagen, Type II, Alpha 1 (Primary Osteoarthritis, Spondyloepiphyseal Dysplasia, Congenital); Collagen II, Alpha-1 Polypeptide; Collagen Alpha-1(II) Chain; Collagen Type II Alpha 1;
Involvement in disease
Spondyloepiphyseal dysplasia congenital type (SEDC):
Disorder characterized by disproportionate short stature and pleiotropic involvement of the skeletal and ocular systems.
Spondyloepiphyseal dysplasia, Stanescu type (SEDSTN):
An autosomal dominant spondyloepiphyseal dysplasia characterized by glycoproteins accumulation in chondrocytes. Clinical features include progressive joint contractures, premature degenerative joint disease particularly in the knee, hip and finger joints, and osseous distention of the metaphyseal ends of the phalanges causing swolling of interphalangeal joints of the hands. Radiological features include generalized platyspondyly, hypoplastic pelvis, epiphyseal flattening with metaphyseal splaying of the long bones, and enlarged phalangeal epimetaphyses of the hands.
Spondyloepimetaphyseal dysplasia, Strudwick type (SEMDSTWK):
A bone disease characterized by disproportionate short stature from birth, with a very short trunk and shortened limbs, and skeletal abnormalities including lordosis, scoliosis, flattened vertebrae, pectus carinatum, coxa vara, clubfoot, and abnormal epiphyses or metaphyses. A distinctive radiographic feature is irregular sclerotic changes, described as dappled in the metaphyses of the long bones.
Achondrogenesis 2 (ACG2):
An autosomal dominant disease characterized by the absence of ossification in the vertebral column, sacrum and pubic bones.
Legg-Calve-Perthes disease (LCPD):
Characterized by loss of circulation to the femoral head, resulting in avascular necrosis in a growing child. Clinical pictures of the disease vary, depending on the phase of disease progression through ischemia, revascularization, fracture and collapse, and repair and remodeling of the bone.
Kniest dysplasia (KD):
Moderately severe chondrodysplasia phenotype that results from mutations in the COL2A1 gene. Characteristics of the disorder include a short trunk and extremities, mid-face hypoplasia, cleft palate, myopia, retinal detachment, and hearing loss.
Avascular necrosis of femoral head, primary, 1 (ANFH1):
A disease characterized by mechanical failure of the subchondral bone, and degeneration of the hip joint. It usually leads to destruction of the hip joint in the third to fifth decade of life. The clinical manifestations, such as pain on exertion, a limping gait, and a discrepancy in leg length, cause considerable disability. ANFH1 inheritance is autosomal dominant.
Osteoarthritis with mild chondrodysplasia (OSCDP):
Osteoarthritis is a common disease that produces joint pain and stiffness together with radiologic evidence of progressive degeneration of joint cartilage.
Platyspondylic lethal skeletal dysplasia Torrance type (PLSD-T):
Platyspondylic lethal skeletal dysplasias (PLSDs) are a heterogeneous group of chondrodysplasias characterized by severe platyspondyly and limb shortening. PLSD-T is characterized by varying platyspondyly, short ribs with anterior cupping, hypoplasia of the lower ilia with broad ischial and pubic bones, and shortening of the tubular bones with splayed and cupped metaphyses. Histology of the growth plate typically shows focal hypercellularity with slightly enlarged chondrocytes in the resting cartilage and relatively well-preserved columnar formation and ossification at the chondro-osseous junction. PLSD-T is generally a perinatally lethal disease, but a few long-term survivors have been reported.
Multiple epiphyseal dysplasia with myopia and conductive deafness (EDMMD):
A generalized skeletal dysplasia associated with significant morbidity. Joint pain, joint deformity, waddling gait, and short stature are the main clinical signs and symptoms. EDMMD is an autosomal dominant disorder characterized by epiphyseal dysplasia associated with progressive myopia, retinal thinning, crenated cataracts, conductive deafness.
Spondyloperipheral dysplasia (SPD):
SPD patients manifest short stature, midface hypoplasia, sensorineural hearing loss, spondyloepiphyseal dysplasia, platyspondyly and brachydactyly.
Stickler syndrome 1 (STL1):
An autosomal dominant form of Stickler syndrome, an inherited disorder that associates ocular signs with more or less complete forms of Pierre Robin sequence, bone disorders and sensorineural deafness. Ocular disorders may include juvenile cataract, myopia, strabismus, vitreoretinal or chorioretinal degeneration, retinal detachment, and chronic uveitis. Pierre Robin sequence includes an opening in the roof of the mouth (a cleft palate), a large tongue (macroglossia), and a small lower jaw (micrognathia). Bones are affected by slight platyspondylisis and large, often defective epiphyses. Juvenile joint laxity is followed by early signs of arthrosis. The degree of hearing loss varies among affected individuals and may become more severe over time. Syndrome expressivity is variable.
Stickler syndrome 1 non-syndromic ocular (STL1O):
An autosomal dominant form of Stickler syndrome characterized by the ocular signs typically seen in Stickler syndrome type 1 such as cataract, myopia, retinal detachment. Systemic features of premature osteoarthritis, cleft palate, hearing impairment, and craniofacial abnormalities are either absent or very mild.
Rhegmatogenous retinal detachment autosomal dominant (DRRD):
A eye disease that most frequently results from a break or tear in the retina that allows fluid from the vitreous humor to enter the potential space beneath the retina. It is often associated with pathologic myopia and in most cases leads to visual impairment or blindness if untreated.
Czech dysplasia (CZECHD):
A skeletal dysplasia characterized by early-onset, progressive pseudorheumatoid arthritis, platyspondyly, and short third and fourth toes.